The bases of these clouds form at about 2000–6200 m above sea level. They are mostly made of water droplets but can contain ice crystals. The clouds are often seen as bluish-grey sheets that cover most, if not all, of the sky. They can obscure the Sun.
The bases of these clouds form at altitudes below 2000 m. They are mostly made of drops of water.
Cumulus – known as fair-weather clouds because they usually indicate fair, dry conditions. If there is precipitation, it is light. The clouds have a flattish base with rounded stacks or puffs on top. When the puffs look like cauliflower heads they’re called cumulus congestus or towering cumulus. They can get very high.